Froth flotation process



Patented Aug. 27, 1935 PATENT OFFICE FROTH FLOTATION PROCESS Oliver 6. Balaton and Clarence R. King, Clarkdale, Ari

Phelps .Dodge Corporation, New York, N. corporation of New York 2;, assignors, by mesne assiznments, to

No Drawing. Application October 6, 1930, Serial This invention relates to the concentration of minerals and has for an object the'provislon of an improved flotation process. More particularly, the invention contemplates the provision of an improved differential flotation process.

The process of the invention involves control of the alkalinity of flotation pulps in order to reject undesirable minerals and permit the recovery of separate concentrates of two or more valuable minerals.

Our invention is particularly adapted for use in conjunction with froth flotation processes involving wet grinding of coarse sulphide minerals or ores, classification of the ground product, and introduction of resulting pulps containing particles of suitable sizes into flotation cells for treatment. According to some heretofore customary practices, an alkaline substance such as lime isadded to the ball mill with the ore or mineral to be ground. Such substances are consumed during the various operations through oxidation and reaction with the sulphide minerals. 'The extent to which the alkaline substance is consumed varies in different operations, and in a single operation in accordance with changes in the character of the ore or mineral being treated and in accordance with changes in conditions, such, for example, as exposure to oxidizing influences and character of grinding, which cannot be controlled exactly.

While consumption of the alkaline substance ,proceedsthrough the grinding, classifying, and

flotation operations, themajor portion is consumed during the grinding operation in the course of which fresh mineral surfaces are being exposed constantly and when conditions are more consumption of alkaline substances varies constantly'in each of the operations involved, it is diflicult to predict the alkalinity of the pulps in the flotation cells when specific amounts of alkaline substances are added with the feed to the grinding mills.

We have found that consumption of alkaline substances proceeds rather uniformly throughout the flotation operation and that'by establishing predetermined amounts of alkaline substances in the feed to the flotation machines, the alkalinecharacter of the pulp in various stages of the flotation operation may be forecast. The desired alkalinity of feed or. pulp entering the flotation cells may be established inany suitable manner, as, for example. by varying the amounts of has... substances added with the feed to the grinding mills, or by adding fixed amounts of alkaline substances with the feed to the grinding-mills and making suitable corrections in the pulp entering the flotation cells.

'We have'also discovered that differential flotation operations involving the treatment of ores containing, sulphides of copper, zinc and iron may be conductedadvantageously when the pulp entering the flotation cells is maintained at an alkalinity equivalent tofrom .01. pounds to 1.0 poundof CaO per ton of water and when suitable mineral collecting, frothing, activating and deactivating agents are employed at appropriate stages. We prefer to employpulps containing two to five parts, by weight of water to one part of ore or minerals.

In treating an ore containing sulphides of copper, zinc and iron, we prefer to first recover a copper concentrate and subsequently recover a zinc concentrate. The zinc concentrate may be retreated to obtain a product higher in zinc. It is desirable to maintain different degreesof alkalinity in the pulps employed in obtaining the rougher copper concentrates and the rougher zinc concentrates and in retreating the rougher zinc concentrates. Generally, satisfactory resultsmay be obtained by treating a pulp of relatively lowalkalinity to recover a rougher copper concentrates-increasing the alkalinity of the resulting tailing pulp to provide a pulp suitable for. the recovery "of a. rougher zinc concentrate, and retreating the zinc concentrate in a pulp in which the alkalinity is 'maintainedat' a value intermediate the values in the pulps employed in obtaining the rougher zinc and copper concentrates. During the flotation operation for the. I recovery of the copper concentrate, we prefer to maintain an alkalinity equivalent to from 0.02 to 0.20 pounds 09.0 per ton of water in the pulp entering the flotation cells. For the subsequent recoveryof a zinc concentrate, we prefer to maintain an alkalinity equivalent to from 0.20 to 1.0 pounds 09.0 per ton of water in the pulp entering the flotation cells. Inretreating the zinc concentrate, we prefer to maintain an alkalinity of from 0.04 to 0.40 pounds CaO per ton. of water in the pulp entering the flotation cells.

As alkaline reagents we may employ one or more of the commonly used reagents such aslime, sodium carbonate and sodium bicarbonate.

While pulps of any desired densities may be employed in the various stages of the process when degrees of alkalinity within the-limits set taining three to four parts by weight of water to one part by weight of ore for the recovery of the copper concentrate, a pulp containing four to five parts by weight of water to one part by weight of ore for the recovery of the zinc concentrate, and a pulp containing one to two parts by weight of water to one part by weight of ore for the retreatment of the zinc concentrate.

Prior to the recovery of the copper concentrate, the ore may be ground advantageously in the presence of lime, water, zinc sulphate and a. suitable alkali or alkaline earth cyanide. Suitable mineral collecting and frothing agents such as an alkali amyl xanthate and pine oil may be added to the feed to the copper flotation cells.

The tailing from the copper flotation cells may be treated in suitable flotation cells for the recovery of a zinc concentrate after correction for alkalinity and with the addition of copper sulphate and suitable mineral collecting and frothing agents such as an alkali amyl xanthate and pine oil. Likewise, retreatment of the zinc concentrate may be conducted in a suitably alkaline pulp and in the presence of similar mineral col- Per cent Zn 6.64 F 66.90

was ground with water, lime, sodium cyanide,

and zinc sulphate. The resulting pulp was sub jected to flotation operations for the recovery of copper concentrates in the presence of potassium amyl xanthate and pine oil under different conditions with respect to alkalinity.

The copper rougher concentrates obtained when using pulps of difierent degrees of alkalinity assayed as follows:-

was ground and the resulting pulp subjected to flotation operations under conditions similar to those described in Example I.

The copper rougher concentrates obtained when using pulps of diiferent degrees of alkalinity assayed as follows:-

The tailings from the operations described in Example II were subjected to flotation operations in the presence of copper sulphate, potassium amyl xanthate and pine oil under different conditions with respect to alkalinity to produce zinc concentrates.

The zinc rougher concentrates and tailings produced assayed as follows:-

C110 content of pulp entering flotation cells 0.0; pounds per ton of 0.7 pounds per ton of water water Concentrates failings Concentrates Tailings Percent Zn. 13. 20 l. 08 .4 1. 00 Percent (-u. 1.11 0.20 1.0 0.22 Percent FeSz 07. 70 74. 10 60.1 75. 00

Example IV The concentrates obtained from the operations described in Example III were retreated in the presence of potassium amyl xanthate and the retreatment tailings were' returned to the feed to zinc rougher cells. Maintenance of from 0.04 to 0.4 pounds CaO per ton of water in the feed to the retreatment cells pe mitted the recovery of final zinc concentrates containing from 48% to zinc. When the feed contained less than 0.04 or more than 0.4 pounds CaO per ton 01. water, a. concentrate containing'more than 45.0% zinc could not be readily produced.

The amounts of mineral collecting and Irothing agents employed may be varied independently of the alkalinity to suit the requirements of ore being treated.

We claim:

1. In a froth flotation process for concentrating ores containing sulphides of copper, zinc andiron and involving the recovery of a copper concentrate followed by recovery of a rougher zinc concentrate and retreatment of the rougher zinc concentrate, the improvement which comprises maintaining an alkalinity equivalent to from 0.02 to 0.20 pounds CaO per ton of water in the pulp entering the copper cells, an alkalinity equivalent to 0.20 to 1.0 pounds CaO per ton of water in the pulp entering the rougher zinc cells, and an alkalinity equivalent to 0.04 to 0.40 pounds CaO per ton of water in the pulp entering the retreatment cells.

2. In a froth flotation process for concentrating ores containing sulphides of copper, zinc and iron and involving the recovery of a copper concentrate followed by recovery of a rougher zinc concentrate and retreatment of the rougher zinc concentrate, the improvement which comprises maintaining an alkalinity equivalent to from 0.02 v to 0.10 pounds CaO per ton of water in the pulp entering the copper cells, an alkalinity equivalent to 0.20 to 1.0 pounds CaO per ton of water in the pulp entering the rougher zinc cells, and an alkalinity equivalent to 0.04 to 0.40 pounds 0110 per ton of water in the pulp entering the retreatmentcellsq 3. The process for obtaining separate copper and zinc concentrates from an ore containing chalcopyrite,,marmatite and pyrites which com-.- prises subjecting the ore in the formof a pulp containing 0.02 to 0.20 pounds CaO per ton of water to a froth flotation operation to recover a copper concentrate, subjecting the tailings from the copper flotation operation in the form of a pulp containing 0.20 to 71.0 pounds CaO per ton of water to a froth flotation operation to recover a zinc concentrate, and subjecting the zinc concentrate to a froth flotation operation in a pulp containing 0.04 to 0.40 pounds CaO per ton of water.

4.. The process for obtaining separate copper and zinc concentrates from an .orc containing chalcopyrite, marmatite and pyrites which comprises subjecting the ore in the form of a pulp containing 0.02 to 0.10 pounds CaO per ton of "water to a froth'flotation operation to a copper concentrate,- subjecting the tailings from the copper flotation operation in the form of a pulp containing 0.20 to 1.0'pounds CaO per ton of water to a froth flotation operation to recover a.

zinc concentrate, and subjecting the zinc concen-' trate to a froth flotation operation in a pulp con-. taining 0.04 to 0.40 pounds CaO per ton of water.

5. In a froth flotation process for concentrating ores containing sulphides of copper, zinc and iron and involving the recovery of a copper concentrate followed by recovery of a rougher zinc concentrate and retreatment' of the rougher zinc concentrate. the improvement which comprises maintaining an alkalinity of'about 0.10 pounds CaO per ton of water in the pulp entering the copper cells, an alkalinity of about 0.70 pounds CaO per ton of water in the pulp entering the rougher zinc cells, and an alkalinity equivalent to 0.04 to 0.40

pounds CaO per ton of water in the pulp entering go the retreatment cells.

OLIVER; C. RALSTON. CLARENCE R. KING. 

